Malicious PDF — malware analysis report

Static analysis result for SHA-256 5db5571876f9ad9a…

MALICIOUS

PDF

44.3 KB Created: 2021-05-11 09:30:40 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-09-29
MD5: d5de5c8d9cf2a6b88ed7e6499a303294 SHA-1: d2941cf8562c5bb165d59c283aa1e5b96b31fe08 SHA-256: 5db5571876f9ad9a5672b68bc5df33cc91088be376bacb0befa68141ef7969d2
222 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

This PDF document contains numerous links to external websites, many of which are disguised as game-related resources like 'free robux' or 'game hacks'. The presence of a fake CAPTCHA lure and instructions for a password-protected archive suggests a multi-stage attack designed to trick users into downloading malicious payloads or revealing credentials. The ML classifier also strongly indicated maliciousness.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9648

Heuristics 7

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • PDF links to a 'free generator / game hack' redirector high PDF_GAME_HACK_REDIRECT_LURE
    PDF's clickable action targets a redirector of the form /app/<id>/<slug>-game-hack — the landing-page shape of a large SEO 'free spins / generator / game hack' lure family that funnels victims through rotating disposable hosts to a malware/scam payload. The multi-link variants also trip ML/link-farm rules; this catches the single-link variants that otherwise score clean.
  • Fake CAPTCHA / human verification prompt high SE_FAKE_CAPTCHA
    Document displays a fake CAPTCHA or human-verification prompt — used to trick users into running commands or pressing keyboard shortcuts
  • Password-protected archive handoff high SE_PASSWORD_ARCHIVE_LURE
    Document gives password instructions for an archive or attachment — often used to keep payloads encrypted until after gateway scanning
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • External URI info PDF_URI
    PDF contains an external URL action
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://netcdn.xyz/app/431946152/roblox-free-robux-hack-game-hack PDF link annotation
    • https://corbo.ru/images/free-robux-websites-that-actually-work_GM431946152.pdfIn PDF document text
    • https://corbo.ru/images/minecraft-skins-download-free_GM479516143.pdfIn PDF document text
    • https://corbo.ru/images/free-spins-promo-code-for-coin-master_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/minecraft-thumbnail-maker-free_GM479516143.pdfIn PDF document text
    • https://corbo.ru/images/free-robux-that-actually-works-2021_GM431946152.pdfIn PDF document text
    • https://corbo.ru/images/coin-master-daily-free-spins-and-coins-2021_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/coin-master-free-spins-link-2021_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/coin-master-free-2021_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/how-many-levels-does-coin-master-have_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/free-daily-spins-coin-master-2021_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/how-to-get-free-spins-on-coin-master-2021_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/roblox-online-free_GM431946152.pdfIn PDF document text
    • https://corbo.ru/images/free-robux-without-human-verification-2021_GM431946152.pdfIn PDF document text
    • https://corbo.ru/images/coin-master-attack-madness-hack_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/free-spins-for-coin-master-2021_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/how-to-get-free-coins-on-coin-master-iphone_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/free-unlimited-coin-master-online-tool_GM406889139.pdfIn PDF document text
    • https://corbo.ru/images/how-to-hack-roblox_GM431946152.pdfIn PDF document text
    • https://corbo.ru/images/how-to-get-free-robux-instantly_GM431946152.pdfIn PDF document text
    • https://corbo.ru/images/free-gold-cards-coin-master_GM406889139.pdfIn PDF document text
    • http://en.wikipedia.org/wiki/MIT_LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_003_off0000457e.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x457E 25460 bytes
SHA-256: 95bd7aa7b679e76f4f8928325cd6be7205a2953377908dfeeee111bf2ab43320
font_01_sfnt_off00007f5b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x7F5B 3016 bytes
SHA-256: 4c3e2db5174821787a4569c9da4979555510caebd15fb9cea35573c139e242bd
font_02_sfnt_off000089be.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x89BE 18488 bytes
SHA-256: 44072fbb5c45a7604268a2c6438126b7db3492802a9c8847ecb07522db400813

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